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Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers

Haugan, Ingrid N. and Maher, Michael J. and Chang, Alice B. and Lin, Tzu-Pin and Grubbs, Robert H. and Hillmyer, Marc A. and Bates, Frank S. (2018) Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers. ACS Macro Letters, 7 (5). pp. 525-530. ISSN 2161-1653. doi:10.1021/acsmacrolett.8b00116.

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The linear viscoelastic behavior of poly(norbornene)-graft-poly(±-lactide) was investigated as a function of grafting density and overall molar mass. Eight sets of polymers with grafting densities ranging from 0 to 100% were synthesized by living ring-opening metathesis copolymerization. Within each set, the graft chain molar mass and spacing between grafts were fixed, while the total backbone length was varied. Dynamic master curves reveal that these polymers display Rouse and reptation dynamics with a sharp transition in the zero-shear viscosity data, demonstrating that grafting density strongly impacts the entanglement molar mass. The entanglement modulus (G_e) scales with inverse grafting density (n_g) as G_e ∼ n_g^(1.2) and G_e ∼ n_g^0 in accordance with scaling theory in the high and low grafting density limits, respectively. However, a sharp transition between these limiting behaviors occurs, which does not conform to existing theoretical models for graft polymers. A molecular interpretation based on thin flexible chains at low grafting density and thick semiflexible chains at high grafting density anticipates the sharp transition between the limiting dynamical regimes.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Haugan, Ingrid N.0000-0002-8406-8939
Maher, Michael J.0000-0003-0577-3726
Chang, Alice B.0000-0001-5036-2681
Lin, Tzu-Pin0000-0001-7041-7213
Grubbs, Robert H.0000-0002-0057-7817
Hillmyer, Marc A.0000-0001-8255-3853
Bates, Frank S.0000-0003-3977-1278
Additional Information:© 2018 American Chemical Society. Received: February 9, 2018. Accepted: March 26, 2018. Publication Date (Web): April 12, 2018. This work was funded by the NSF through the Center for Sustainable Polymers (CHE-1413862) and under award number CHE-1502616. This research used resources of the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Part of this work was performed at the DuPont–Northwestern–Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the APS. DND-CAT is supported by E.I. DuPont de Nemours & Co., The Dow Chemical Company, and Northwestern University. The authors declare no competing financial interest.
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC02-06CH11357
E.I. DuPont de Nemours & Co.UNSPECIFIED
Dow Chemical CompanyUNSPECIFIED
Northwestern UniversityUNSPECIFIED
Issue or Number:5
Record Number:CaltechAUTHORS:20180412-141958464
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Official Citation:Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers. Ingrid N. Haugan, Michael J. Maher, Alice B. Chang, Tzu-Pin Lin, Robert H. Grubbs, Marc A. Hillmyer, and Frank S. Bates. ACS Macro Letters 2018 7 (5), 525-530. DOI: 10.1021/acsmacrolett.8b00116
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85792
Deposited By: George Porter
Deposited On:12 Apr 2018 21:44
Last Modified:15 Nov 2021 20:32

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